Akaganéite

Formula: b-FeO(OH,Cl)

Origin of name:  Locality; Akagane mine, Iwate Pref., Japan

Crystal system:  Monoclinic

Crystal class: 2/m

Twinning:

Unit cell: a = 10.651 Å, b = 3.031 Å, c = 10483 Å, b = 90.63°

Colour:  Brown, yellowish brown; 

Diaphaneity: Semitransparant

Luster: Adamantine, metallic

Habit:  Fine-grained masses, powdery

Hardness:

Specific gravity:  3.0 to 3.5

Cleavage:  None

Tenacity:

Streak: Brownish yellow

Synonyms/varieties:

Comments:  Polymorphous with feroxyhyte, goethite and lepidocrocite; from several sources including iron meteorites. Apparently formed from pyrrhotite by ferric-sulphate-bearing solutions. An important constituent in some soils, and certain geothermal brines and in seafloor nodules.